Red azo-dyestuffs and a process for their manufacture



Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE RED AZO-D'YESTUFFSAND A PROCESS FOR THEIR MANUFACTURE Oskar Knecht and Theodor Wirth,Basel, Switzerland, assignors to the firm of Chemical Works, formerlySandoz, Basel, Switzerland No Drawing.

Application November 9, 1935, Se-

rial No. 49,110. In Switzerland November 21,

2 Claims.

5 formula S02 It BIO: HO

N Rx/ \R2 sols wherein R1 stands for a benzene nucleus and R2 representsa radical free from hydroxy groups, selected from the class consistingof alkyl, aralkyl and aryl, which are in the dry state red to brown-redpowders, soluble in water with a red coloration and dyeing animal fibresred shades of excellent fastness properties.

The following examples, without being limitative, illustrate the presentinvention.

Example 1 27.6 parts of 1-aminobenzene-2-sulphonylethyl-anilide arediazotized with 6.9 parts of sodium nitrite and 25 parts of hydrochloricacid of 30 per cent strength and the clear yellow diazo solution isadded to an acetic acid solution of 24 parts of2-amlno-8-hydroxynaphthalene-6-sulphonic acid; the excess of mineralacid is then neutralized by an addition of sodium acetate and thedyestuffs salted out with common salt, filtered and Washed with a commonsalt solution. It constitutes, after drying, a brown-red powder, veryeasily soluble in water.

The dyestuff dyes wool a clear red shade; the dyeing is very level andpossesses a good fastness to light.

Example 2 32 parts of l-aminobenzene-2sulphonyldiphenylamide arediazotized in an acetic acid solution with 6.9 parts of sodium nitriteand 25 parts of hydrochloric acid of 30 per cent strength, diluted withwater, and the whole is allowed to run into an acetic acid solution of24 parts of 2- amino-S-hydroxynaphthalene-6-sulphonic acid. Afterneutralization of the excess of mineral acid by means of an addition ofsodium acetate, the precipitated dyestufi is filtered, Washed with acommon salt solution and dried. It constitutes a brown-red powder, whichis easily soluble in water and dyes wool a clear bluish-red tone. Thedyeing is exceedingly level and shows a very good fastness to light andfulling.

Example 3 34 parts of 1-aminobenzene-Z-sulphonylethyl-2'-methoxy5'-chloroanilide are diazotized with 6.9 parts of sodiumnitrite and 25 parts of by drochloric acid of 30 per cent strength. Thecoupling with 24 parts of 2-amino-8-hydroxynaphthalene-G-sulphonic acidand the isolation of the dyestuff are carried out as described inExample 2.

The dyestufi thus obtained constitutes a brownred powder, which iseasily soluble in water. The dyeings are very level and possess a goodfastness to light and fulling.

Example 4 35.2 parts of l-aminobenzene-2-sulphonylbenzyl-m-toluidide arediazotized in an acetic acid solution with 6.9 parts of sodium nitriteand 25 parts of hydrochloric acid of 30 per cent strength and copulatedwith 24 parts of 2-amino-8-hydroxynaphthalene-6-sulphonic acid in themanner described in Example .2.

The dyestufi thus obtained is a red powder, easily soluble in water,dyeing wool a clear bluishred shade. The dyeing is extraordinarily leveland possesses a good fastness to light and fulling.

What we claim is:-

1. Red monoazo-dyestufis of the general formula Slog HO N l SOzH R1 R2wherein R1 stands for a benzene nucleus and R2 represents anunsubstituted alkyl group, said dyestuffs being in the dry state red tobrown-red powders, soluble in water with a red coloration and dyeinganimal fibres red shades of excellent fastness properties.

which is in the dry state a brown-red powder, 10 easily soluble in waterwith a red coloration and which dyes animal fibres fast red shades.

OSKAR KNECHT. THEODOR WIRTH. 15

